Carbon brush



R. L. ADAMS CARBON Bnusfl' Sept. 7, 1937.

Filed April 27, 1935 w. ;s rm Wmodour mi t f w Patented Sept. 7, 1937CARBON BBUSH Roy' L. Adams. Schenectady, N. Y., asaiznor to GeneralElectric Company, a corporation of New York v Application Api-ii 27,1935, serial No. 18,599 i 3Claima.

The present invention relates to a method for ioining copper to carbonand more particularly to carbon brushes for dynamo electric machines anda method for making the same.

One of the objects of the present invention is to provide a lowresistance connection between a carbon brush and the flexible conductorusually employed to carry current to or from the brush.

The novel features which are characteristic of my invention are setforth with particularity in the appended claims. The inventlon itselfhowever will best be understood from reference to the followingspecification when considered in-connection with the accompanyingdrawing in which Flg. 1 is a view in elevation of a carbon brushembodying the features of my invention, while Fix. 2 is a crosssectional view of a modified form of my invention.

In carrying out my invention I apply a layer of flnely divided copper toa carbon block l. The block and copper are then heated at an elci'atedtemperature, for example about 600 C.-to 800 C., but below the meltingpoint of the copper, while pressure is simultaneously ,applied to thecopper to force it into the adjacent pores of the carbon and to weld thecopper particles into a solid mass 2. During the heating process, anysulphur in the carbon block I ris to the upper surface thereof and formsa compound with a portion of the copper providing thereby anintermediate layer I of copper sulphide. A flexlble connector l may besecured to the welded copper mass 2 in a manner well known in the art.

Instead of applying pulverled copper to the carbon block as hereinbeforeindicated, it usually will be found preferable to apply a cupreousmaterial such as pulverized copper sulphide directly to the carbon blockand to heat the copper sulphide and carbon block to a temperature of.about 600 to 800' C. while pressure is simultaneously applied to thecopper sulphide. An excess of copper sulphide is employed so thattheadjacent pores of the carbon block will be fllled or imprenated and alayer of copper sulphide oorrespondinz to layer 8 of Fig. 1 provided ontop of the carbon. A copper plate corresponding to the welded coppermass 2 may then be secured to the layer of copper sulphide in anydesired manner, for example by brazing, after which a flexible conductor4 may be secured to 5 the copper plate. The intermediate layer of coppersulphide is secured to the carbon with such great tenacity that if :anattempt is' made to separate'the copper sulphide from the carbon thebreak will occur in the carbon rather than at the junction of the coppersulphide layer and the carbon.

Instead of applying flnely divided copper or I copper sulphide to theentire upper surface of the carbon block I may provide an opening in theupper surface of a carbon brush 5 and fill it with pulverized copper orcopper sulphide 6 into which a flexible conductor 'l may be insertedafter which pressure and heat may be applied to the pulverized materialas hereinbefore set forth.

While my invention is partlcularly adapted for use in connection withcommutator brushes it will be obvious that it is not limited to such useand that it may be employed in connection with carbon contacts and thelike or in any device where a particularly strong connection betweencopper and carbon is desired.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. A carbon block provided with a layer of cop-- per sulphide thereon,the pores of said block adjacent said layer being impregnated with saidsulphide.

which comprises applying pulverizedl copper sulphide to a carbon block,heating the block and copper sulphide at an elevated temperature, whilepressure is simultaneously applied to the copper sulphide.

' BOY L. ADAMS.

